The assumed rate of future mortality improvement has increased over three recent sets of the United Kingdom's national population projections. This optimism has not been so marked in countries which share ancestors with the U.K. population. New Zealand is one such country that provides a data-rich case example in which to investigate the portability of mortality trends.This paper compares mortality trends in New Zealand with those in England & Wales. Both countries seem to have a ‘golden cohort’ which enjoys faster improving mortality than people born before or after. The birth of the golden cohort in England & Wales coincided with cohort life expectancy there catching up with New Zealand's.We show that first generation migrants from the U.K. have better mortality than New Zealand born residents likely to have British ancestry. The advantage lasts into older ages, decades after migration. We hypothesise that migrants from the U.K.'s golden cohort brought with them an early life mortality improvement advantage, and additionally benefited from the healthier environment of New Zealand at middle to older ages. Further, given the recent strong mortality improvement in New Zealand, the U.K.'s assumptions for future mortality look relatively optimistic.

How long people expect to live sets an important context for longevity risk in retirement planning and may contribute to the acceptability of policies to raise pension age. However, there have been few studies representative of a national population on subjective longevity. This paper reviews the available evidence. It finds that despite some studies reporting that subjective longevity is close to average measures in population life tables the prevailing tendency is to underestimate lifespans. Men generally reflect that they have lower actual longevity than women on average, but men are more optimistic, so that women are more likely to underestimate their likely longevity. People may take account of some mortality risk factors in estimating their own longevity, but appear not to understand the true extent of risk. There is little data on how people think about longevity or why they choose a particular estimate of their own likely lifespan. Thus, international evidence suggests potential for longevity risk in individual retirement planning and raises significant questions about the policy implications which can only become more acute in ageing populations.

<p>The pace of increasing life expectancy in recent decades came as a surprise to demographers, as mortality rates unexpectedly improved at the oldest ages in developed countries. The most common policy response, although one not yet planned for New Zealand, is to increase eligibility age for the public pension. Given the complexity and uncertainty of processes driving mortality improvement, future lifespans cannot be known. However, it is questionable whether policy makers and individuals understand the extent of past and likely future lifespan increase. Available evidence suggests individuals tend to underestimate how long they may live. Population mortality forecasts are generally conservative and poorly explain longevity uncertainties. Longevity risk - the possibility that future lifespans will be longer than anticipated - threatens individuals' pre-retirement financial planning and public pension policy. This thesis examines the extent of longevity risk, its causes, significance and remedies, in these two domains, for New Zealand. The theoretical existence of longevity risk has been acknowledged, but has not been subject to critical analysis in New Zealand or elsewhere. Here, a unique generalisable methodology exploiting insights available from international mortality comparisons is designed, combining actuarial and demographic theory. After assessing the flaws in the time-dependent or period approach to measurement of life expectancy that are known in theory but underexplored in practice, the method emphasises the lifecourse or cohort approach. The three factors that determine longevity risk - plausible population lifespan prospects, the lifespan assumptions used by policy makers and individuals' subjective lifespan expectations - are identified and the relationships between them analysed for New Zealand. An interpretation of the consistency of New Zealand's past mortality trends and future projections with those of other British settler countries, supplemented by a review of the consequences of mortality variance within New Zealand, shows that plausible lifespans in New Zealand are likely to be higher than those in the official projections on which policy makers rely. The first survey to ask how long New Zealanders think they will live shows that collectively, New Zealanders are more likely to underestimate future lifespan than not, based on a variety of beliefs about mortality that are not consistent with the evidence on increasing lifespans. Longevity risk from underestimation of future lifespans is revealed in New Zealand policy making and in individual New Zealanders' retirement plans. The most likely cause is the repeated misuse of life expectancy indicators in an environment lacking public discourse about increasing longevity. A remedy would be switching from using flawed period life expectancy indicators to using cohort life expectancy or modal age at death. Using plausible estimates for future lifespans based on more optimistic estimates than the official projections most often referenced would be important but mitigate longevity risk to a lesser extent. A more extensive public debate than has been held so far about eligibility age for New Zealand's public pension would itself, if using appropriate indicators for future lifespans, provide an opportunity to address longevity risk.</p>